JPH0675189B2 - Lithography mask structure and photolithography processing method using the same - Google Patents

Description

The present invention relates to a mask structure used in lithography. Such a mask structure is used, for example, in manufacturing a semiconductor device. Furthermore, the present invention relates to a photolithography processing method using a mask structure.

[Prior Art] It is widely used industrially, particularly in the field of electronics, to manufacture various products by partially modifying the surface of a work material by using a lithographic technique. A large amount of products having the same surface alteration can be manufactured. The alteration of the surface of the material to be processed is carried out by irradiation with various energy rays. At this time, a mask in which an energy ray absorbing material is partially arranged is used for pattern formation. As such a mask, when the irradiation energy ray is visible light, a black coating is partially applied on a transparent substrate such as glass or quartz, or a visible light absorbing thin plate of metal such as Ni, Cr. Alternatively, a thin film partially provided has been used.

However, in recent years, along with the demand for finer pattern formation and the demand for a lithography processing technique in a shorter time, X-rays and particle beams such as ion beams have come to be used as irradiation energy rays. Most of these energy rays are absorbed when passing through the glass plate or the quartz plate used as the mask forming member in the case of the visible light. Therefore, when using these energy rays, it is not preferable to form the mask using a glass plate or a quartz plate. Therefore, in the lithography processing technique using X-rays or particle beams as irradiation energy rays, various inorganic thin films such as silicon nitride, boron nitride,
Silicon oxide, a thin film of titanium or the like, or various organic thin films such as polyimide, polyamide, or a thin film of polyester or the like, further using a laminated film thereof as an energy transmitting body, gold, platinum, nickel, tungsten on these surfaces, A mask is formed by partially applying a metal such as palladium, rhodium or indium as an energy ray absorber. Since this mask does not have self-shape retention, it is supported by an appropriate holder.
As a mask structure constructed in this way, a mask structure whose cross-sectional view is shown in FIG. 11 has been conventionally used. This is because the energy ray-absorbing mask material 1 is applied on one side in a desired pattern to the peripheral portion of the energy ray-transmitting holding thin film 2 on one end surface (the upper end surface in the figure) of the annular holding substrate 3 with an adhesive. It was formed by sticking using 4. In addition,
FIG. 12 is a plan view of the holding substrate 3.

By the way, when performing the photolithography process using the above-described mask structure, the mask pattern of the mask structure is accurately measured with respect to the work material such as a silicon wafer (the surface of which is coated with photoresist). It is necessary to perform the alignment (alignment) and to accurately set the gap (gap) between the surface of the workpiece and the mask material holding thin film of the mask structure.

Therefore, in the conventional lithography process using a mask structure, marks for alignment are provided on the surface of the work material and the holding thin film of the mask structure, and the holding thin film is placed after being substantially parallel to each other. Alignment is performed by irradiating a visible light beam from the side while detecting the degree of matching of both marks, and the gap is set while detecting the reflected light on the surface of the holding thin film and the reflected light on the surface of the workpiece. It was

However, in such detection, visible light transmitted through the holding thin film is detected, so that the detection accuracy is lowered due to scattering and / or absorption in the holding thin film, and the photon of sub-micron order or less is detected. It is not possible to obtain sufficient alignment and gap setting accuracy in lithography.

Further, in order to improve the detection accuracy of the alignment mark, it is possible to use electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays instead of visible rays, but these are significantly scattered and absorbed by the holding thin film. So virtually unusable.

[Object of the Invention] In view of the above-mentioned conventional techniques, it is an object of the present invention to provide a lithographic mask structure capable of performing alignment with a work material and setting a gap with high accuracy. A further object of the present invention is to provide a photolithography processing method using the mask structure as described above.

[Outline of the Invention] According to the present invention, for achieving the above-mentioned object, for lithography in which a peripheral portion of a mask material holding thin film to which a mask material is to be applied in a desired pattern on a surface is held by a holding substrate. In the mask structure, the mask material holding thin film composed of a laminated body of an organic thin film and a metal thin film is provided with a plurality of through holes through which energy rays for detecting an alignment state with a workpiece can be passed. Provided is a mask structure for lithography, wherein a through hole is provided at a position corresponding to a scribe line of a material to be processed.

Further, according to the present invention, in order to achieve the above objects, a mask structure for lithography in which a peripheral portion of a mask material holding thin film having a mask material applied in a desired unit pattern on its surface is held by a holding substrate. Through the body, a work material having a plurality of regions divided by scribe lines was irradiated with a first energy ray, and the plurality of regions were applied to the mask material holding thin film of the mask structure. A photolithography processing method for transferring a unit pattern, wherein as the mask structure, a plurality of mask material holding thin films formed of a laminate of an organic thin film and a metal thin film are provided at positions corresponding to scribe lines of the work material. The mask structure having a through hole is used, and the second energy ray is passed through the through hole provided in the mask structure. A photolithography processing method, which comprises irradiating the first energy beam after detecting an alignment state between the mask structure and the processing material and making the relative positions of the mask structure and the processing material correspond to each other. , Are provided.

[Embodiment] FIG. 1 shows a plan view of a specific example of the mask structure for lithography according to the present invention. Figure 2 is II-II in Figure 1.
FIG. 3 is a sectional view taken along line (however, FIG. 1 and FIG. 2 do not completely match). This specific example is a mask structure for X-ray photolithography.

The mask material 1 is applied to one surface of the holding thin film 2 in a desired pattern. As the mask material 1, for example, a thin film of about 0.5 to 0.7 μm such as gold, platinum, nickel, tungsten, tantalum, copper, molybdenum, palladium or rhodium can be used.

The peripheral portion of the holding thin film 2 is adhered to the annular holding substrate 3 with an adhesive 4. The holding thin film 2 is composed of a laminated body of an organic thin film and a metal thin film.

As the organic thin film, a thin film of polyester, polyamide, polyimide, parylene or the like can be used. The thickness of the organic thin film is, for example, about 2 to 20 μm. This organic thin film is preferably used in a state of being stretched isotropically at a stretching ratio of, for example, about 5 to 20% (area ratio) from the viewpoint of maintaining good flatness.

As the metal thin film, a thin film of titanium, copper, gold, platinum, chromium, tin, nickel, aluminum or the like can be used. The thickness of the gold thin film is, for example, 0.01 to 1.0 μm
It is a degree. Such a metal thin film can be formed by a thin film deposition method such as vapor deposition.

The holding thin film 2 may be composed of one layer of organic thin film and one layer of metal thin film, or may be composed of two or more layers of organic thin film and metal thin film, respectively. Since the holding thin film 2 of the present invention is composed of a laminate of an organic thin film and a metal thin film, it has various properties such as mechanical strength, thermal conductivity, and electrical conductivity.

As the holding substrate 3, for example, silicon, glass, quartz, phosphor bronze, brass, iron, nickel, stainless steel or the like is used.

As the adhesive 4, for example, an epoxy type, a rubber type, or other appropriate type is used, for example, a solvent type, a thermosetting type, or a photocuring type.

The holding thin film 2 is provided with a plurality of small holes 5 (four holes in the figure) which penetrate from the front surface to the back surface at positions where the masking agent 1 is not applied.

The shape of the small hole 5 is not particularly limited, and may be a rectangle such as a square or a rectangle, a triangle such as a triangle, a hexagon, or an octagon, a circle such as a circle or an ellipse, or a combination thereof. However, a circular shape is particularly preferable from the viewpoint of preparation. The size of the small hole 5 is not particularly limited, depending on the alignment with the target workpiece, the state of the gap, the type of energy ray used for detection, and the required detection accuracy, etc. It can be set appropriately.
Examples of energy rays used for detection include electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays, and visible rays and infrared rays can also be used. As an example, when the detection is performed using an electron beam, the diameter of the small hole 5 is about 10 to 30 μm.
The number of the small holes 5 is about 2, and the number of the small holes 5 is two or four in axial symmetry with respect to the symmetry axis of the annular holding substrate 3. However, small hole 5
The position where is provided is appropriately set according to the pattern of the mask material 1 in the mask structure.

3 (a) and 3 (b) are enlarged views of the portion of the small hole 5 in FIG. 1 and FIG. 2, respectively, and FIG. 3 (b) is BB of FIG. 3 (a). It corresponds to a sectional view. As shown in the figure, the holding thin film 2 is a laminated body of an organic thin film 2a and a metal thin film 2b. Since the organic thin film and the metal thin film are generally subjected to different treatments when forming the small holes 5, their diameters are different, and the diameter of the metal thin film 2b is small.

4 (a), (b), 5 (a), (b) and 6
3 (a) and 3 (b) are shown in FIGS. 3 (a) and 3 (b), respectively.
Another embodiment of a portion similar to is shown. In these embodiments, the small holes 5 are not just openings, but have bridging portions 5a. The bridging portion is formed by the metal thin film 2b,
The organic thin film 2a has the same structure as in the case of FIG.
And in FIGS. 4-6, the planar shape of the said bridge | bridging part 5a differs, and thus the pattern of the small hole 5 differs.

In the photolithography process such as a semiconductor device manufacturing process, as shown in FIG. 7, a large number of semiconductor devices 11 having the same pattern are formed on a semiconductor wafer 10 as a workpiece. These semiconductor elements 11 are cut into boundary lines (scribe lines) 12 after forming a pattern to be each semiconductor element chip.

In such a photolithography process, as the pattern of the mask material 1 of the mask structure, a pattern in which a plurality of unit patterns of the semiconductor element are arranged in parallel is used. In FIG. 1, the unit pattern 7 of the semiconductor element is 4
Individually arranged. These unit patterns 7 are
The line 8 is divided by the line 8 corresponding to the scribe line 12 of the semiconductor wafer 10. In photolithography, the predetermined scribe line 12 of the semiconductor wafer 10 and the corresponding line 8 of the mask structure 13 are accurately associated with each other. Alignment is performed (see FIG. 8), and then energy rays such as X-rays are irradiated. And
Further, the relative positions of the semiconductor wafer 10 and the mask structure 13 are changed, and the unirradiated semiconductor element group is subjected to alignment and energy ray irradiation in the same manner as above, and this is repeated.

The semiconductor wafer 10 is provided with alignment marks formed as, for example, recesses at appropriate positions on the scribe line 12 by etching or the like. Like this
When the alignment mark is formed on the scribe line 12 of the semiconductor wafer 10, the small hole 5 in the mask structure has a line corresponding to the scribe line corresponding to the alignment mark as shown in FIG. 8 is formed. The scribe line of the semiconductor wafer 10
12 has a width of, for example, about 30 μm, and the alignment mark is formed with a size smaller than that. In this case, it is preferable that the small hole 5 has a diameter of about 15 μm.

The method of forming the small holes 5 in the holding thin film 2 is appropriately selected according to the material of the holding thin film 2. For example, a method using a laser beam (excimer laser, argon laser, etc.), a method using dry etching (RIE oxygen plasma, etc.) Examples thereof include chemical etching (hydrazine-based etchant, etc.) and mechanical means (milling, etc.). Of course, these methods may be used in combination of two or more. As described above, the organic thin film 2a and the metal thin film 2b may be formed by different methods when forming the small holes 5, and the metal thin film 2b may have a relatively high shape and dimension accuracy. Therefore, the small holes may be formed in the organic thin film 2a with relatively low accuracy.

It is preferable to form the small holes 5 in a step close to the final step of forming the mask structure, which can prevent a decrease in the small hole position accuracy due to post-processing.

Good patterning accuracy can be realized by performing pattern formation for forming small holes at the same time as the step of forming the mask material 1 on the holding thin film 2.

As shown in FIG. 9, the mask structure 13 as described above is
At the time of use, it is used in close proximity to the semiconductor wafer 10. A resist layer 14 is formed on the surface of the semiconductor wafer 10. While moving the mask structure 13 in the left-right direction relative to the semiconductor wafer 10, the small holes 5 are irradiated with an electron beam from above to detect secondary electrons generated from the semiconductor wafer 10. The detection value of the secondary electrons differs depending on the presence or absence of this realignment mark (for example, a concave portion as shown in the figure), and the arrangement when the detection value takes an extreme value is such that the mask structure 13 is arranged with respect to the scribe line 12 of the semiconductor wafer. This is a state in which the small holes 5 are accurately arranged. By similarly detecting the plurality of small holes 5, the relative positional relationship between the semiconductor wafer 10 and the mask structure 13 can be made accurate. Similarly, when measuring the gap, the electron beam that has passed through the small hole 5 is measured. Of course, a method of detecting focus shift by an optical lens can also be used.

During the irradiation of the electron beam, the detection accuracy is further improved in the case of the small hole 5 having the pattern having the bridging portion 5a as shown in FIGS.

In addition to the above-mentioned electron beam, an ion beam, an X-ray, etc. may be used as an energy ray used for alignment or detection of a gap when the mask structure of the present invention is used.
Lines, ultraviolet rays, vacuum ultraviolet rays, and also visible rays and infrared rays can be used, and if the alignment mark on the side of the material to be processed is formed to show a behavior different from those of the surrounding energy rays. Good.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1: A mask structure having a vertical sectional view shown in Fig. 10 was prepared.
10, the same members as those in FIG. 2 are designated by the same reference numerals. In this embodiment, no adhesive is applied to the upper flat end surface 3a of the annular holding substrate 3,
An adhesive 4 is applied to the slope 3b on the upper outer side, whereby the holding thin film 2 and the holding substrate 3 are bonded. It is suitable that the angle θ of the inclined surface is about 5 to 15 degrees, and in this embodiment, it is set to 10 degrees.

According to such a mask structure of this embodiment, the mask material holding plane of the holding thin film 2 is not affected by the adhesive 4 and realizes good flatness with the flatness of the upper flat end surface of the holding substrate 3 being unchanged. It is possible to improve the accuracy of lithography processing.

First, the polyimide film (about 7.5 μm) is isotropically stretched with the adhesive 4 on the annular holding substrate 3 at a stretch ratio of about 10%.
Thickness, Kapton film (trade name) was adhered.

Then, deposit about 0.1 μm on the polyimide film by vacuum deposition.
A thick nickel (Ni) film was formed, and thus a holding thin film composed of a laminate of a polyimide film and a nickel film was formed.

Next, on the surface of the nickel film, photoresist AZ-1350
(Made by Shipley Co., Ltd.) is applied to a thickness of 0.5 μm under specified conditions,
Approximately 20 μm in diameter with a quartz mask using a deep UV printing machine
A resist pattern having four small holes was formed.

Next, the nitric acid-based etchant was used to carry out chemical etching of the nickel film at the small hole pattern position to form four small holes in the nickel film.

Next, with the nickel film as a mask, the polyimide film at the small hole pattern position was etched away using a hydrazine-based etchant to form small holes.

Thus, as shown in FIG. 3, four small holes 5 which penetrate the holding thin film 2 were formed.

Using the four small holes 5 as a reference, about 0.5 is formed on the surface of the nickel film by electroforming in a predetermined process.
An X-ray absorption pattern made of a metal having a thickness of μm was formed.

Example 2: In the same manner as in Example 1, titanium (T
i) (about 0.2 μm thick) -using a gold (Au) (about 0.05 μm thick) film and using a polyester film (about 6 μm) instead of the polyimide film.
A mask structure was prepared using a thickness, manufactured by Toray Industries, Inc., product surface mirror.

In this example, small holes having a diameter of about 25 μm were formed in the titanium-gold film, and at this time, an iodine-based etchant was used for etching the gold film and a nitric acid-based etchant was used for etching the titanium film. Further, pulse exposure by an excimer laser was used when forming small holes having a diameter of about 30 μm in the polyester film.

Incidentally, in this example, the X-ray absorption pattern was not formed.

Example 3: In the same manner as in Example 1, a mask structure having a holding thin film in which a nickel film having a thickness of about 0.05 μm was formed on both surfaces of a polyimide film was prepared.

In this example, the small holes of the two nickel films were formed at the corresponding positions, and the small holes of the polyimide film were formed using the nickel films as a mask.

Example 4 Similar to Example 1, a mask structure having small holes 5 having a pattern as shown in FIG. 4 was prepared.

In this embodiment, when forming the small holes of the nickel film, the first embodiment is performed.
A mask different from that in the above case was used, and the bridging portion 5a made of a nickel film was formed in the small hole portion. The small holes of the polyimide film were formed in the same manner as in Example 1.

Example 5: In the same manner as in Example 4, a mask structure having small holes 5 having a pattern as shown in FIG. 5 was prepared.

[Advantages of the Invention] According to the present invention as described above, in the lithography process, when the mask structure is aligned with the workpiece and the gap is set, the energy beam irradiation is performed through the through hole provided in the mask material holding thin film. By doing this, it is possible to detect the reflection from the work material with little scattering and absorption, so that it is possible to perform alignment and gap setting with high accuracy, thereby enabling highly accurate lithography processing. You can

Further, according to the present invention, since the mask material holding thin film is composed of a laminated body of an organic thin film and a metal thin film, the through small hole end surface of the organic thin film which has high strength but is relatively flexible and easily deformed is aged. It can be kept in good condition without changes and thus accurate alignment can be achieved.

Further, since the holding thin film has a metal thin film, the holding thin film is prevented from being charged by grounding the metal thin film during alignment by, for example, an electron beam, so that more accurate alignment can be performed. This effect is further increased by forming the holding thin film as a laminated body composed of three layers of a metal thin film / organic thin film / metal thin film.

In addition, since the holding thin film has the metal thin film, it is possible to pattern the through hole, which allows more accurate alignment and prevents the shape of the through hole from changing with time.

[Brief description of drawings]

FIG. 1 is a plan view of the mask structure of the present invention, and FIG. 2 is a II-II sectional view thereof. 3 to 6 are enlarged views of the through hole portion. FIG. 7 is a partial plan view of the work material, and FIG. 8 is a partial cross-sectional view showing the relationship between the work material and the mask structure. FIG. 9 is a partial sectional view showing a usage state of the mask structure of the present invention. FIG. 10 is a sectional view of the mask structure of the present invention. FIG. 11 is a sectional view of a conventional mask structure, and FIG. 12 is a plan view of its holding substrate. 1: Mask material, 2: Holding thin film 2a: Organic thin film, 2b: Metal thin film 3: Holding substrate, 4: Adhesive 5: Small hole 8: Line for scribe line 10: Work material, 12: Scribe line 13: Mask Structure, 14: Resist layer

Claims (8)

[Claims] 1. A mask structure for lithography in which a peripheral portion of a mask material holding thin film to which a mask material is applied on a surface in a desired pattern is held by a holding substrate, which is composed of a laminate of an organic thin film and a metal thin film. The mask material holding thin film is provided with a plurality of through holes through which energy rays for detecting the alignment state with the workpiece can be passed.
A mask structure for lithography, wherein the through hole is provided at a position corresponding to a scribe line of a material to be processed. 2. The mask structure for lithography according to claim 1, wherein the energy beam is an electron beam. 3. The energy beam is an electron beam, and the through hole provided in the mask material holding thin film has a diameter of 10 to 10.
The mask structure for lithography according to claim 1, wherein the mask structure has a thickness of 30 μm. 4. A lithographic mask structure in which a peripheral portion of a mask material holding thin film having a mask material applied in a desired unit pattern on its surface is held by a holding substrate,
The work material having a plurality of regions divided by the scribe line is irradiated with the first energy ray, and the unit pattern given to the mask material holding thin film of the mask structure is transferred to the plurality of regions. In the photolithography processing method, as the mask structure, a plurality of through holes are provided at positions corresponding to scribe lines of the material to be processed in a mask material holding thin film composed of a laminate of an organic thin film and a metal thin film. The second energy beam is passed through a through hole provided in the mask structure to detect the alignment state between the mask structure and the work material, and the mask structure and the work material are used. The photolithography processing method is characterized by irradiating the first energy ray after making the relative positions thereof correspond to each other. 5. The photolithography processing method according to claim 4, wherein the first energy rays are X-rays. 6. An alignment mark is formed at a predetermined position on a scribe line of the work material, and a through hole provided in the mask structure is formed corresponding to the alignment mark. The photolithography processing method according to claim 4, which is characterized in that. 7. The photolithography processing method according to claim 4, wherein the second energy beam is an electron beam. 8. An alignment mark is formed at a predetermined position on a scribe line of the workpiece, and a through hole provided in the mask structure is formed corresponding to the alignment mark. An electron beam as a second energy ray is passed through a through hole provided in the mask structure to irradiate a scribe line of a corresponding work material to detect a secondary electron, and the secondary electron is detected. A fourth aspect of the present invention is characterized in that the relative positions of the mask structure and the workpiece are made to correspond to each other according to the value.
The method of photolithography according to item.